Air bag in an air bag unit

ABSTRACT

In an air bag (1) in an air bag unit, which is inflated by high pressure gas from an inflator operated in an emergency, it is formed by woven cloth in hollow weave where edges (2) are at least partially provided in single weave (6). Because the air bag (1) is formed from woven cloth in hollow weave, the air bag (1) can be manufactured simply by forming the base cloth (5) of the air bag (1) in advance, which is made of woven cloth in hollow weave with its part in single weave (6) and by cutting the base cloth (5) at the single weave portion (6). In this case, because a part of the desired portion can be woven in single weave and the other can be woven mechanically in hollow weave in cylindrical shape, the above base cloth (5) can be easily manufactured. This eliminates such procedures as the procedure to cut a plurality of air bag components into the desired shape and the procedure to sew up the cut components by aligning the edges. As the result, it is possible to reduce the steps of manufacturing process to a great extent and to mechanize the air bag production. Therefore, the productivity of the air bag can be extensively increased, and the air bag can be produced at lower cost.

FIELD OF THE INVENTION

The present invention relates to an air bag unit for protecting anoccupant in a vehicle by absorbing the shock caused during vehiclecollision, and in particular to an air bag in an air bag unit forreceiving the occupant pushed forward as the bag is inflated by highpressure gas from an inflator at the collision.

TECHNICAL BACKGROUND

An air bag unit is installed on a fixed portion of car body in front ofseat in a vehicle. In an emergency such as vehicle collision, the airbag is inflated instantaneously by the pressure of reaction gas releasedfrom an inflator, which is fixed on a fixed portion of car body such assteering wheel or lower portion of instrument panel. Thus, the air bagplays an important role for protecting the occupant from injury causedby collision against car body.

As shown in FIG. 7, such air bag unit 01 comprises an inflator 02, whichreleases gas as gas generating agent is exploded by collision signalfrom collision detecting sensor when the deceleration of the vehicleexceeds a certain level, and an air bag 03, which is fixed with respectto the inflator 02 at its base and is inflated by the gas blown out fromthe inflator 02. With the air bag 03 folded up and placed in a pad, theair bag unit 01 is mounted on a fixed portion of the car body such ascentral portion of a steering wheel 04 or lower portion of instrumentpanel 05.

Then, as shown in FIG. 7, the gas generating agent in the inflator 02reacts when the vehicle is collided, and the air bag 03 isinstantaneously inflated and expanded by the generated gas. As theresult, the air bag 03 receives the occupant M, who is pushed forward byinertia and protects the occupant M from the collision against car body.

Of such air bag 03 in an air bag unit 01, the air bag 03 for an occupantother than the driver is formed as shown in FIG. 8 (A) as follows: Froma piece of base cloth, bag main unit 03a and a pair of lateral segments03b and 03c, against which the occupant strikes, are cut into thepredetermined shapes, and these are sewn up with lugs as shown in FIG. 8(B).

However, when a plurality of the components (03a, 03b and 03c) of theair bag 03 are cut from a piece of base cloth and are sewn, many stepsof processes are required.

Moreover, because it is difficult to mechanize the sewing of base clothand the sewing of edges, all these works must be done manually, and theworks need much labor because there are many points to sew up.

For this reason, the productivity of air bag has been not very high inthe past.

To solve the above problems, the object of the present invention is tooffer an air bag in an air bag unit, by which it is possible to reducethe number of manufacturing steps and to increase the productivitythrough mechanization.

SUMMARY OF THE INVENTION

To overcome these difficulties, the air bag according to the presentinvention is characterized in that a part of edges are formed at leastpartially from woven cloth woven by hollow weaving in single weave.

By the air bag of this invention with such arrangement, it is possibleto manufacture air bag by producing an air bag base cloth from wovencloth of hollow weave with a certain portion woven in single weave andby cutting the base cloth on single weave because the air bag is made ofwoven cloth in hollow weave. In this case, a predetermined portion canbe woven in single weave and the other portions can be wovenmechanically in hollow weave, weaving in cylindrical form. Thus, theabove base cloth can be produced in simple manner.

For this reason, it is possible to reduce the working steps to a greatextent and to mechanize the production of air bag because thecomplicated working procedure can be eliminated such as the procedure tocut a plurality of air bag components into predetermined shapes or theprocedure to sew up the edges of these components.

This contributes to extensive increase the productivity of the air bagand to manufacture the air bag at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of an air bag in an airbag unit according to the present invention;

FIG. 2 shows the manufacturing process of this air bag, where (A) is adrawing of base cloth to be used for the manufacture of the air bag, (B)is a cross-sectional view of FIG. 2 along the line II B--II B, (C) is adrawing of component of the air bag, which is formed by cutting basecloth into a predetermined shape, and (D) shows an air bag componentformed in the desired shape;

FIG. 3 shows the variations of the air bag in FIG. 1, where (A) is adrawing similar to FIG. 1 (D), (B) is a cross-sectional view of FIG. 3(A) along the line III B--III B, and (C) is a side view of the air bagwhen it is inflated;

FIG. 4 is a drawing similar to FIG. 2 (A) showing a variation of basecloth;

FIG. 5 shows another embodiment of the present invention, where (A) is adrawing similar to FIG. 2 (A), (B) is a cross-sectional view of FIG. 5(A) along the line V B--V B, (C) is a cross-sectional view of FIG. 5 (A)along the line V C--V C, and (D) is a drawing similar to FIG. 2 (C)showing a cut component of the air bag;

FIG. 6 is a drawing similar to FIG. 5 (D) showing a variant of the airbag of FIG. 5;

FIG. 7 shows a commonly used air bag unit, which is installed in avehicle; and

FIG. 8 shows a conventional type air bag, where (A) shows the componentsof the air bag, and (B) is a perspective view when the components aresewn up.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In an air bag 1 of FIG. 1, the edges 2 are formed by hollow weavethrough single weave of lateral cloths a and b. The air bag 1 isprovided with an opening 3 at upper end, while the bottom is formed inrectangular shape. When inflated, it has a form of truncated cone (ortruncated pyramid or a composite of these two). An inflator (not shown)is inserted into the air bag 1 through an opening 3, and the opening 3is fixed on the inflator.

FIG. 2 shows a base cloth used for the manufacture of the air bag 1, andit also shows the manufacturing process of the air bag 1.

As shown in FIG. 2 (A), the base cloth 5 of the air bag 1 is woven incylindrical shape. As it is evident from FIG. 2 (B), it is formed from awoven cloth in hollow weave where the predetermined portion is woven insingle weave 6. This single weave portion 6 is provided to match theshape of the air bag to be produced.

As shown in FIG. 2 (A) , by cutting the base cloth 5 along the line(a)--(a) on a single weave portion 6, the air bag component 7 shown inFIG. 2 (C) is formed. The air bag component 7s is cut along the line(b)--(b) to provide an opening, and the portions c and d of the air bagcomponent 7 are overlapped and bonded 8 by adequate methods such assewing, bonding, welding, etc. Thus, an air bag member 9 with its bottomin approximately rectangular shape can be obtained. By putting this airbag member 9 inside out, the air bag 1 of FIG. 1 is formed. In thiscase, the portions c and d may be partially cut.

In such air bag 1, the air bag 1 can be manufactured simply by cuttingthe base cloth 5 in hollow weave with its part woven in single weaveinto the predetermined shape on the single weave portion and by bonding8 to adjust the shape of the air bag. In such case, unlike theconventional case where a plurality of components cut into thepredetermined shape are sewn up by aligning the edges, bonding isperformed by simply bonding at the predetermined positions, and muchlabor is not required for such procedure. Therefore, it contributes tothe reduction of the processes to manufacture the air bag 1 and to theproduction of air bag 1 in short time and at low cost.

Moreover, it is possible to mechanize the air bag production because theprocedure such as the procedure to cut a plurality of air bag componentsand the procedure to sew up by aligning the edges can be eliminated.

Further, to produce an air bag for an occupant other than the driver,the portion "e" may be bonded together by adequate method such assewing, bonding or welding as shown in FIGS. 3 (A) and (B). As theresult, it is possible to form an air bag 1 of top mount type for theabove occupant, in which the directions of the opening 3 and the bottom4 are varied by a predetermined angle as shown in FIG. 3 (C).

FIG. 4 shows a variant of the base cloth 5. the variants and otherembodiments described below, the same component is referred by the samesymbol, and detailed description is not given.

In FIG. 4, the base cloth 5 of hollow weave has its part in single weaveportion 6 as in the case of base cloth shown in FIG. 2 (A). In thisembodiment, the single weave portion 6 is formed in trapezoid. As theresult, the opening for the inflator is provided, and the strength ofthe portion (lower portion in the figure) where inflator is attached canbe increased.

In the above embodiment, the opening 3 where the inflator is inserted isformed by cutting along the line (b)--(b) in FIG. 2 (C), whereas theopening 3 may be formed at the other adequate position as shown bytwo-dot chain line in FIG. 2 (C).

FIG. 5 shows another embodiment of this invention.

As shown in FIGS. 5 (A)-(C), in the base cloth 5 of hollow weave,lateral shape of a cylindrical portion 9 (i.e. the portion other thanthe single weave portion 6) is formed in an approximately circularshape. It is cut along lateral shape of the cylindrical portion 9 sothat the edges 2 are formed with a predetermined width, and an air bagmember 10 is formed as shown in FIG. 5 (D). After providing the opening3 at the desired position of this member 10, an air bag of approximatelycircular shape is formed by putting inside out. This air bag is used asan air bag for a driver of a vehicle.

FIG. 6 shows a variant of the air bag of FIG. 5.

In an air bag member 11 of this variant, an edge 2 of single weave isprovided over total periphery of the circular cylindrical portion 9. Inthis embodiment, an air bag is formed by putting inside out after anopening for inserting the inflator is provided at the desired position.

Because no sewing process is required for the air bag of the embodimentshown in FIG. 5 and FIG. 6, the steps of the manufacturing process canbe reduced further. In addition, it is easier to mechanize themanufacturing process.

APPLICABILITY FOR THE INDUSTRY

The air bag in an air bag unit according to the present invention can beused on a vehicle and applied for the purpose of protecting the occupantby absorbing the shock which occurs when the vehicle is collided.

What is claimed is:
 1. An air bag for an air bag unit that is inflatedby high pressure gas from an inflator, comprising:a hollow weave cloth;two opposite edges of said hollow weave cloth being at least partiallyprovided in single weave; said two opposite edges converging toward oneanother such that the air bag has a narrow width at one end and asubstantially greater width at an opposite end; and wherein portions ofsaid air bag at said two opposite edges at said opposite end having asubstantially greater width are overlapped and bonded so that asubstantially rectangular shape can be formed at said opposite end ofthe air bag.
 2. The air bag for an air bag unit of claim 1, wherein saidair bag includes an opening for injecting high pressure gas adjacentsaid one end having a narrow width.
 3. The air bag for an air bag unitof claim 2, wherein said opening is formed by a cut portion of thehollow weave at said one end.
 4. The air bag for an air bag unit ofclaim 2, wherein said opening includes a cut portion in a side surfaceof the hollow weave next to said one end.
 5. A method of making an airbag unit, comprising the steps of:providing a generally cylindricallywoven base cloth; providing a first single wave portion and a secondsingle weave portion which converge toward one another toward a firstend of the base cloth from an opposite second end of the base cloth;cutting the base cloth along the first and second single weave portionsso as to separate an individual air bag; and further including the stepsof providing a third single weave portion on a side opposite said secondsingle weave portion from said first single weave portion, and providingeach the first, second and third single weave portions in a generallytrapezoidal shape so as to form air bags which converge in the samedirection.
 6. The method of claim 5, further including the step ofcutting an opening for injecting high pressure gas into the individualair bag.
 7. The method of claim 6, wherein said step of cutting saidopening is formed such that the opening is at said first end.
 8. Amethod of making an air bag unit, comprising the steps of:providing agenerally cylindrically woven base cloth; providing a first single weaveportion and a second single weave portion which converge toward oneanother toward a first end of the base cloth from an opposite second endof the base cloth; cutting the base cloth along the first and secondsingle weave portions so as to separate an individual air bag; andfurther including the step of overlapping portions of the individual airbag at said second end and bonding these portions so as to form agenerally rectangular shape at said second end.
 9. The method of claim8, further including the step of bonding a side portion of the air bagbetween said first and second single weave portions so that the air bagwill open in a predetermined angle when inflated.